A MONOGEAPH 



ON 



CARBONICOLA, ANTHRACOMYA, AND NAIADITES. 



§ I. INTRODUCTION. 1 



The fossils to be described in this Monograph are obtained, almost without 

 exception, from the productive Coal-measures of the Carboniferous Series ; whether 

 they occur, as in Scotland, the North of Ireland, and the North of England, at the 

 base of this formation, as well as in the Coal-measures proper ; or, as in the other 

 coal-fields of Ireland, the remainder of England and Wales, and the Continent, 

 above the Millstone-grit, in the upper beds. They chiefly occur in ironstone bands 

 or nodules in indurated marl, and in black carbonaceous shales, and often in such 

 profusion as to constitute shell-beds which extend over large areas. 



On the Continent it is found that the genera occurring in the Coal-measures 

 pass up into beds of Permian age ; but it is doubtful at present whether it can be 

 shown that the same species survived through both periods. 



It is not within the scope of this Monograph to attempt the correlation of the 

 various strata found in the different coal-fields of Great Britain ; indeed, the 

 Author believes that it would be impossible to do so, from the fact that the nature 

 and thickness of the coal-seams and intervening beds undergo such alterations in 

 the same coal-field that the conditions affecting the deposit must have been very 



1 In working up the Bibliography of the bivalve Mollusca of the Coal-measures I have been 

 reluctantly obliged to acknowledge that in two at least of the three genera to be described in this 

 Monograph the names now in use must be abandoned for others which have the priority. M'Coy's 

 name of Carbonicola, though accompanied by a partly erroneous diagnosis, is undoubtedly a few 

 months older than King's Anthracosia, in which, too, the hinge characters described belong to a 

 species, and not to the genus. And also there is no doubt that Prof. J. W. Dawson's Naiadites is 

 older than Salter's Antkracoptera, although Dawson's genus originally contained members of all the 

 genera to be described in this work. 



1 



